3-羟基-2-吡啶亚胺异构反应的机理

在RHF-6-31G,MP2/6-31G和MP2/6-31G水平上,对3-羟基-2-吡啶亚胺的气相、水分子作为催化剂的异构化反应进行了研究,结果表明,气象异构难于进行,水分子作为催化剂参与反应过程是目标反应所循的反应路径。     

α-Al2O3相变机理及制备工艺研究进展

α-Al2O3在耐火材料、电子材料等多个领域有着极其重要的应用.本文首先介绍了α-Al2O3在工业应用方面的评价指标和α-Al2O3的相变机理,接着分别从固相合成、液相合成、气相合成三个方面阐述了α-Al2O3制备的相关研究进展,对制备过程中影响α-Al2O3晶粒微观状态的若干因素,包括煅烧温度、矿化剂类型、pH值及预...     

两种高分子化锌卟啉络合物与特丁津相互作用的光谱性能研究

将苯基卟啉(PP)功能化的聚甲基丙烯酸缩水甘油酯(PGMA)即PP-PGMA和羟基苯基卟啉(HPP) 功能化的PGMA(HPP-PGMA)分别与锌离子发生络合反应,制得高分子化的苯基锌卟啉ZnPP-PGMA或羟苯基锌卟啉ZnHPP-PGMA。采用¹H-NMR对ZnPP-PGMA和ZnHPP-PGMA的化学结构进行了表征,用紫外-可见光谱法、荧光光谱法研究了其光谱性能。将ZnPP-PGMA或ZnHPP-PGMA与特丁津作用,研究特丁津对其光谱性能的影响。研究结果表明:高分子化的金属卟啉ZnPP-PGMA和ZnHPP-PGMA都具有强的光谱性能,相对于PP-PGMA和HPP-PGMA,其电子吸收光谱Soret吸收带红移,荧光发射峰蓝移。ZnPP-PGMA和ZnHPP-PGMA分别与特丁津作用后,ZnPP-PGMA的紫外光谱发生一定程度的红移,且ZnPP-PGMA和ZnHPP-PGMA发生明显的荧光猝灭现象。随着特丁津浓度的增大,ZnHPP-PGMA发生荧光猝灭的程度增大。     

过渡金属钴配合物催化Suzuki-Miyaura交叉偶联反应催化活性组分生成机理的理论研究

采用密度泛函理论(DFT)对过渡金属钴配合物催化Suzuki-Miyaura交叉偶联反应生成Co(Ⅰ)配合物(~(iPr)PNP)Co OR的反应机理进行了理论研究.结果表明,在反应过程中(~(iPr)PNP)配体中的一个膦配体从金属中心解离生成INT1',且三重态下的解离路径为优势反应路径;由INT1'生成Co(I)配合物(~(iPr)PNP)CoOR的解离反应路径中协同机理比分步机理更具优势;对底物ROH[R=Me,Et,~iPr,CH(Ph)Me]的R基团进行了调变,研究了生成(~(iPr)PNP)CoOR的解离路径的协同机理和分步机理中底物基团调变效应,当R=~iPr时反应的能垒最高.     

Insights into the adsorption of water and oxygen on the cubic CsPbBr3 surfaces: A first-principles study

The degradation mechanism of the all-inorganic perovskite solar cells in the ambient environment remains unclear. In this paper, water and oxygen molecule adsorptions on the all-inorganic perovskite (CsPbBr₃) surface are studied by density-functional theory calculations. In terms of the adsorption energy, the water molecules are more susceptible than the oxygen molecules to be adsorbed on the CsPbBr₃ surface. The water molecules can be adsorbed on both the CsBr- and PbBr-terminated surfaces, but the oxygen molecules tend to be selectively adsorbed on the CsBr-terminated surface instead of the PbBr-terminated one due to the significant adsorption energy difference. While the adsorbed water molecules only contribute deep states, the oxygen molecules introduce interfacial states inside the bandgap of the perovskite, which would significantly impact the chemical and transport properties of the perovskite. Therefore, special attention should be paid to reduce the oxygen concentration in the environment during the device fabrication process so as to improve the stability and performance of the CsPbBr₃-based devices.     

含氮杂环协助的醛胺缩合反应机理的研究

采用密度泛函理论（DFT）方法研究了在酸性条件下对带有氮杂原子的伯胺与醛的缩合反应机理.研究结果表明,在酸性条件下,碱性更强的杂环氮比羰基氧更容易被质子化,杂环氮作为氢质子桥使缩合反应能垒大大降低,计算得到的反应能量跨度为13.08 kcal/mol.同时,将伯胺上含氮杂环上的N原子调变为P,As原子及改变N原子的位置后缩合反应能垒升高,证实了杂环氮原子协助氢转移的重要性,此理论研究为揭示含氮杂环伯胺与醛的缩合反应机理提供了新的思路与理论依据.     

双核过渡金属络合物引发氮分子活化研究

将自然界资源丰富但化学性质上极其惰性的氮气分子在温和条件下转化为氨及其他含氮化合物,具有非常重要的意义。过渡金属络合物引发氮分子的活化及官能化已成为现代工业固氮的一大研究热点。本文回顾了氮分子与双核过渡金属络合物结合的键型模式,总结了影响氮分子活化的诸多因素如配体调变效应、金属调变效应等,对双核过渡金属络合物引发的双氮裂解、双氮官能化及CO/CO2协助双氮活化官能化等反应的实验与理论研究现状和进展进行了简要综述,并对未来过渡金属络合物在氮分子固定的应用发展作了展望。     

甲醇羰基化制乙酸反应的理论研究

采用有效核势能近似(ECP)从头算方法, 在LANL2DZ基组下研究了铑碘络合物催化剂催化甲醇羰基化制乙酸的反应机理. 优化得到了反应基态势能面的反应物、过渡态和产物的几何构型. 理论计算结果说明, 该催化反应循环中CH₃I氧化加成、羰基插入和CH₃COI还原消除基元反应步骤的活化位垒分别为216.03, 128.10和126.56 kJ/mol, CH₃I氧化加成是整个反应的决速步骤.     

Coupling interaction between a single emitter and the propagating surface plasmon polaritons in a graphene microribbon waveguide

The coupling interaction between an individual optical emitter and the propagating surface plasmon polaritons in a graphene microribbon （GMR） waveguide is investigated by numerical calculations, where the emitter is situated above the GMR or in the same plane of the GMR, The results reveal a multimode coupling mechanism for the strong interaction between the emitter and the propagating plasmonic waves in graphene. When the emitter is situated in the same plane of the GMR, the decay rate from the emitter to the surface plasmon polaritons increases more than 10 times compared with that in the case with the emitter above the GMR.